Manufacture of gelatinous silica.



STATES PATENT orrucn.

ANDREW rouLsoN, or rAnNwomH, NEAR wnmEs, ENGLAND.

MANUFACTURE or ennArmoossrnrcA.

No Drawing.

Specification of Letters Patent. Application filed December 28, 1909. segiial Ito-#235,245,

' Patented Dec. 26, 1911.

To all whom it may concern:

Be it known that I, ANDREW POULSON, a subject of the King of England, residing at Hope House, Farnworth, near Widnes, in the county of Lancaster, invented certain new and useful Improvements in the Manufacture of Gelatinous Silica; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to an improved process formanufacturing elatinous silica which is more economical ant? which produces more readily a better commercial product than the processes now, in use.

In making the gelatinous silica I make a dilute solution of silicate of soda and water of the density of about Twaddell, havinga specific gravity of about 1.125 andcontaining about 12?; per cent. of sodium silicatc. This solution I mix withdilute commercial hydrochloric acid of about 15\TWad-' dell, or 1.07 5 specific gravity containing about 15 per cent. of HCL, the acid being preferably very slightly in excess. j

No artificial heat is needed. The mixed solution is allowed to stand and I have foundthat in from 24 to 36 hours gelatinization is complete.

The gelatinous silica thus formed may be broken up and washed with water to remove any iincombined solution and to dissolve out the sodium chlorid and whatever excess of acid there may be present.

Commercial silicate of soda almost always contains sodium bicarbonate or sodium carbonate.

In the manufacture of a gelatinous silica sometimes a solution of silicate of soda has been mixed with a decomposing agent, such as an acld and the salts present have been diflicult or impossible to remove except bydialysis. In some cases sodium bicarbonate or sodium carbonate has been added to the solution of silicate of :soda before treatment with the acid, but in all these cases there has remained intermingled with the gelatinous mass either carbon dioxid or a sodium carbonate.

Now I find that by my invention according to which-I use very dilute solutions, no visible efiervescing formation of carbon dioxid takes place but on the contrary any 'that is formed dissipates before the gela- England, have tinizationis' completed so that the gelatinous silica is free of it.

Sodium chlorid is present in the gelatinous mass ,formed according to my invention but I find that this salt is very readily removed therefrom and does not cling to or. intermesh with the silica.

A distinguishing-characteristic of my invention is the large amount of water present as compared with other processes for, the manufacture, of gelatinous silica, and this dilution appears, to allow the exchange of atoms between the hydrochloric acid and the silicate of soda to be'more even and to produce a more pure and homogenous mass of gelatinous silica than where more concen- -trated solutions are used. The reaction is gentler.

' If solutions of reagents having much greater specific gravity than those which I have specified above are employed, the

gelatinization of the resulting mixture 00- curs very. much more rapidly, and as a result, the carbon dioxid formed is not given an opportunity to escape, and is entangled to a great extent in the viscous and gelatinous mass. The bubbles of carbon dioxid ma be very minute, and in fact almost in- ViSlbl" but their effect is to cause retention of large quantities of sodium chlorid or -other salts and-consequently, it is practically impossible to remove the sodium chlorid completely 'no matter how often the y washing with water is repeated. On the other hand, if the solutions employed are much lessin density, the resulting mixture 1. The process of making gelatinous silica I which comprises mingling a solution of sodium silicate of about 1.125 specific gravity with dilute hydrochloric acid of about 1.075 specific gravity, and allowing the resulting mixture to gelatinize.

2. The process of making gelatinous silica which comprises mingling a solution of 1.075'spe'cific gravity, allowing the resulting mixture to stand without artificial heating until gelatinization is complete, breaking up the gelatinous mass so formed and washing with water to remove soluble matter. v I

In testimony whereof I hereunto aflix my signature in the presence of two witnesses.

ANDREW POULSON. Witnesses:

H. WATSON, CHAS. COVENTRY. 

